The liquid crystal display, by right of its characteristics such as low power consumption, relatively low manufacture cost and free of radiation etc., has become the mainstream of the flat panel display and has been widely used in electronic devices such as mobile phones, computers, televisions etc.
The main structure of the liquid crystal display comprises an array substrate formed by box aligning, a color film substrate and a liquid crystal layer located between the array substrate and the color film substrate. Its principle is controlling torsion of liquid crystal molecules in the liquid crystal layer through an electric field so as to control light transmittance of the liquid crystal layer; moreover, a black matrix (BM) and a color layer matrix (RGB) are formed on the color film substrate, which implement the functions of light shielding and light filtering respectively. During the process of manufacturing the liquid crystal display, the black matrix (BM), the color layer matrix (RGB) and a pillar spacer (PS) on the color film substrate generally adopt negative photoresists and are formed through processes such as coating, proximity exposing, developing, roasting etc. Specifically, referring to FIG. 1 and FIG. 2, in the proximity exposure process, the exposure light passes through the opening area of a mask plate 1′ and irradiates a surface of a negative photoresist 2′ on a substrate 3′, a polymerization reaction will occur in the photoresist area that contacts the light to form a macromolecular chain with high intensity, then a matrix 21′ will be formed on the surface of the substrate 3′ after the processes of developing and roasting, while the photoresist area that does not contact the light will be dissolved or peeled off in the development process. However, in the exposure process, referring to FIG. 3 and FIG. 4, the mask plate comprises a light shielding area 11′ and an opening area 12′, the edge of the opening area 12′ in the mask plate is in a linear shape; when the exposure light passes through the opening area 12′ of the mask plate, due to the diffraction of the light source, there is a difference between the light intensities to which opening areas of different mask plates correspond, particularly at the edge of the opening area, the light intensity to which it corresponds is relatively low (the smaller the line width of the opening area is, the more obvious such a difference is), thereby influencing the surface hardening effect of the negative photoresist at the edge of the opening area. In the subsequent development process, the photoresist at the edge of the opening area absorbs water and expands, the stress increases, lateral deformation is easily produced, which results in bending of the edge of the matrix 21′ (as shown in FIG. 5), thereby enabling the matrix edge of the color filter in the color film substrate to generate a jagged or a wavy shape rather than the desired linear type, resulting in badness (such as nonuniformity of color display of the subsequently formed display). Particularly in the process of forming a black matrix (BM) with a line width less than 10 μm, such a phenomenon is more obvious.